Teardown revives hopes that Lightning might be USB 3.0-compatible

Earlier today we linked to iFixit's iPhone 5 teardown, and there's something interesting lurking in the pictures of the Lightning connector. Although it's clear at this point that the iPhone 5 only sports USB 2.0 speeds, initial discussions of Lightning's support of USB 3.0 have focused on its pin count—the USB "Super Speed" 3.0 spec requires nine pins to function, and Lightning connectors only have eight.

The Lightning connector itself has two divots on either side for retention, but these extra electrical connections in the receptacle could possibly be used as a ground return, which would bring the number of Lightning pins to the same count as that of USB 3.0—nine total.

If this is the case, then it shows that Apple has at least thought ahead with its new plug, and may have future-proofed it to support USB 3.0. This would be a wise tactical move on Apple's part and could open the door to Lightning being used to supplement Thunderbolt as a second high-speed standard port, rather than as a one-off iPhone connector competing awkwardly with USB 2.

Of course, the need for extra pins is obviated if the connector's shield can be used as the ground return; in that case, the extra pins are just extra pins, which would be used in some form or fashion for Lightning signaling. As usual, Apple is mum on the details and no official confirmation exists one way or another.

Apple spokespersons have confirmed that HDMI and VGA cables utilizing Lightning will be available soon, so the interface is clearly destined for more than just USB 2.0 data syncing.

90 Reader Comments

Really? Apple, the company that has been using the 30-pin for 12 years might have thought ahead with their new connector that's pissed people off for having changed? That's its not just a proprietary format for the sake of it, and might offer huge advantages over something like micro-USB? Who would have thought...

I suspect the extra pins will be used to electrically connect to the slug of aluminum that is the plug.

Also, let's not forget the plug is reversible, and as Tim said, the pins are not dedicated, their function is digitally negotiated. If each of the side-divots is electrically distinct, and both sides of the connector are used for different data lines, with the device controller sorting out the details, that leaves us an eighteen-pin dock connector. Thunderbolt is a 20-pin protocol, but eight of them are grounds. Two of them are reserved grounds, which might be used specifically for return on the low speed transmit and return lines, or later used to add a second low-speed Tx and Rx pair. Let's give them their own pins because why not.

That brings Thunderbolt down to a 15-pin interface. Even if the divots are only used as a high-power ground return, we can handle thunderbolt signaling over Lightning. Which, remember, is only using Mini Displayport as a plug of convenience. And Sony is using a USB based plug for Thunderbolt, and everyone else is sort of sitting this out.

What if Lightning is the port Apple designed for the specific purpose of a Thunderbolt-native plug? That just happens to be backwards-compatible with USB, firewire, and everything else?

Looks to me like those extra pins might merely be what provides the ground connection to the shielding. Seems like they would line right up with the silver on either edge of the Lightning connector.

Here's my prognostication about Lightning... it's going to turn out that it's basically just USB 3.0 in a different form factor. There's already evidence that the backwards compatibility with the the analog audio and serial comm parts of the 30-pin requires a chip in Apple's new adapter. Digital video out for the old connector and the new connector both require a separate dongle and in neither case are there dedicated DV pins (the dongles in both cases are probably just converting USB video into HDMI, with some DRM magic as required by the studios).

Of course Lightning is going to be USB 3 compatible. Eventually it will be Thunderbolt compatible as well. Watching folks freak out about this right now has been amusing, if slightly embarrassing. They're giving away the USB 2 plug because that's what *everyone* has. USB 3 and Thunderbolt will be available, at a price, for those who want it.

Of course, I've already been saying that Lighting would be natively USB3 compatible in the comments to your last two Lighting articles. It's really a "no duh" proposition, and I didn't even have to look at the iFixit teardown to make that educated guess. Furthermore, it's the only thing that makes sense. Apple doesn't want to make unnecessarily complicated smart cables to translate from USB3 to the iDevice, and making the iDevice more complicated so it can talk a multitude of interfaces is silly too. The cheapest and most elegant solution (and hence, the most Apple thing to do) is make the Lighting connector pin-for-pin USB3 compatible

I think it's pretty important. Fortunately, the cable has a repairability score of 10/10.

It easily unplugs from both the iPhone and any attached peripheral without any tools whatsoever -- only a slight tug is required.

The defective cable can then be thrown in the trash and replaced with a functional replacement by inserting the connector ends into the sockets provided therefore and pushing lightly until the connector is engaged -- all without any tools whatsoever.

So no, there is no way that they could, or would, ever use the shield as the ground return. That would effectively render most of the effects of the shield moot.

Furthermore, the shield is not connected directly to ground at the phone-end. In fact, it is sometimes (though I'm not familliar with the USB spec) not even grounded at both ends. If you ground both ends, you wind up with some of your ground current flowing over the shield, and that affects the shield's ability to, well, shield.

The only way I can think of to run a USB-3 connection over 8 pins (plus shield) would be to use only one ground-return, rather then the specced GND and GND_DRAIN, and that would likely impact the ability of the connector to carry power, as well as possibly impacting data reliability.

-----------

Really, the only way the lightning connector could ever support USB-3 would be by either having different connections on either side (making it effectively a 16 pin connection), or using an apple-proprietary extention to USB-3 that uses fewer pins (but would not be compatible with generic USB-3 devices).

This article is really rather blatantly ignorant of anything regarding the actual engineering behind USB-3.0. It discusses USB-3.0 as bing "nine pins", when the pinout *included in the article* even includes 10 connections. Just because the shield does not have a pin-number does not mean it's not needed.

Really, the only way the lightning connector could ever support USB-3 would be by either having different connections on either side (making it effectively a 16 pin connection), or using an apple-proprietary extention to USB-3 that uses fewer pins (but would not be compatible with generic USB-3 devices).

Has anyone verified in the teardowns that both sides route to the same place? If they go to separate pins, it's entirely possible that Apple installed an auto-switching chip (similar to an auto-switching port for Ethernet).

I suspect the extra pins will be used to electrically connect to the slug of aluminum that is the plug.

Yeah, they're ground pins

Quote:

Also, let's not forget the plug is reversible,

Lightning is reversible, but there's only 8 pins in the port. The reversibility is for user convenience only.

Quote:

and as Tim said, the pins are not dedicated, their function is digitally negotiated.

So are the connectors in any device that supports MHL. I doubt Lightning goes any further than that.

Quote:

If each of the side-divots is electrically distinct,

They're not, they're grounding pins, they ground to the shield of the plug, which means when the plug is inserted they're electrically connected to each other.

Quote:

and both sides of the connector are used for different data lines, with the device controller sorting out the details, that leaves us an eighteen-pin dock connector. Thunderbolt is a 20-pin protocol, but eight of them are grounds. Two of them are reserved grounds, which might be used specifically for return on the low speed transmit and return lines, or later used to add a second low-speed Tx and Rx pair. Let's give them their own pins because why not.

That brings Thunderbolt down to a 15-pin interface. Even if the divots are only used as a high-power ground return, we can handle thunderbolt signaling over Lightning. Which, remember, is only using Mini Displayport as a plug of convenience. And Sony is using a USB based plug for Thunderbolt, and everyone else is sort of sitting this out.

Sony's LightPeak port includes a fiber optic link.

Quote:

What if Lightning is the port Apple designed for the specific purpose of a Thunderbolt-native plug? That just happens to be backwards-compatible with USB, firewire, and everything else?

Thunderbolt is massive overkill and unnecessary. As it stands now, Lightning can likely already output video via MHL, and device storage is still so slow that even USB2 is underutilized when transferring data to it.

Really, the only way the lightning connector could ever support USB-3 would be by either having different connections on either side (making it effectively a 16 pin connection), or using an apple-proprietary extention to USB-3 that uses fewer pins (but would not be compatible with generic USB-3 devices).

Has anyone verified in the teardowns that both sides route to the same place? If they go to separate pins, it's entirely possible that Apple installed an auto-switching chip (similar to an auto-switching port for Ethernet).

I assume nobody has gotten around to buzzing the board out yet...

From the teardown images, the connector in the phone actually only connects to one side (look at the pin the pulled out of the connector). As such, the iPhone 5 cannot ever support USB-3.

There have not been any teardowns of the cable-end that I have seen, and it's entirely probably that apple would release a new cable to go with the new device that supports USB-3, so taking apart current cables would be pointless.

The point I was trying to make is that the connector, as described currentlycannot EVER support standard USB-3.

So no, there is no way that they could, or would, ever use the shield as the ground return. That would effectively render most of the effects of the shield moot.

They're not using the shield as a ground return, they're just not using the shield at all. Certainly however there is a shield in the cable itself that connects as usual via the conventional USB connector on the host side.

You mean, "current proofed it" since USB3 is pretty standard on new machines right now.

No it's not. We're talking about handhelds here, not PCs. A high speed interconnect is worse then pointless if the bottleneck is storage itself. Small Flash cells are not at all inherently fast. The huge speeds in SSDs come from smart, relatively larger and power hungry controllers, power hungry RAM caches, and exploiting massive parallelism across many individual cells and dies. Even at 64 GB SSDs experience significant performance drops purely by virtue of less cells to write, and that's without considering power and cost considerations. Using older asynchronous NAND (probably ONFI 1.0) is cheaper and more power efficient for example.

To take the iPhone in particular, a number of places have benchmarked its primary storage. Apple multisources its NAND of course, but even so rates have generally been pretty similar. The iPhone 4 and iPhone 4S both maxed out at around 20-22MB/s sustained sequential transfer speed. That is well below the point of even vaguely saturating USB 2.0. I haven't seen that tested on the iPhone 5 yet, but even if they tripled the NAND performance USB 3 would be effectively pointless, and probably more power and die hungry to boot.

It'll only be in future years that this will become a problem, as solid state storage continues to improve. So for a connector design it's very much a matter of future proofing, not "current proofing". It's a foreseeable issue within even a pessimistic estimate for the lifetime of the connector, but not right now.

So no, there is no way that they could, or would, ever use the shield as the ground return. That would effectively render most of the effects of the shield moot.

They're not using the shield as a ground return, they're just not using the shield at all. Certainly however there is a shield in the cable itself that connects as usual via the conventional USB connector on the host side.

No no no no no. You don't understand what the shield is for. It's being used simply by being there, and being grounded at one end.

Basically, the shield prevents environmental EMI from getting to the conductors inside of it. Any EMI gets absorbed by the shield, and shunted to ground by the fact that the shield is grounded.

In fact, the shield is absolutely essential to proper USB functioning. Try removing the shield from a USB connection, and see how well it works.

----

Whoops, I think I may have not understood your response correctly. The shield and the metal casing of the connector are the same thing. They're tied together. That way, the shield extends through the connector.

Apple spokespersons have confirmed that HDMI and VGA cables utilizing Lightning will be available soon, so the interface is clearly destined for more than just USB 2.0 data syncing.

It's designed to replicate the functions of the old cable, but using much less space due to better logic.

I can't think why Apple would keep USB 3.0 compatibility a secret, but you never know with them I suppose. Certainly you can't necessarily trust Apple to prioritize consumer convenience over making as much money as possible.

Basically, the shield prevents environmental EMI from getting to the conductors inside of it. Any EMI gets absorbed by the shield, and shunted to ground by the fact that the shield is grounded.

In fact, the shield is absolutely essential to proper USB functioning. Try removing the shield from a USB connection, and see how well it works.

----

Whoops, I think I may have not understood your response correctly. The shield and the metal casing of the connector are the same things. They're tied together. That way, the shield extends through the connector.

You said it yourself. The shield in USB isn't connected to anything on the device side. So there can be a shield within the cable that connects as usual on the host side, and if the body of the Lightning plug acts as the ground, then that effectively gives them 9 pins and they're golden.

Remember that Lightning is a digital connection. That would indicate to me that with a software driver and a cable -- like the Thunderbolt cable -- a USB 3.0 interface could be created. The Thunderbolt cable is a smart cable with circuitry inside.

The Lightning to 30 pin adapter has circuitry inside the adapter to make it work. The adapter is not simply a box that routes wires from the 8 Lightening pins to pins on the 30 pin adapter. It's a smart adapter. When you plug it into the iPhone the iPhone knows thats a 30 pin adapter is connected and sends digital signals through the 8 pins into the adapter and the adapter then converts that digital data into what is needed to support the old 30 pin dock connector.

The Lightning connector was designed by Apple to be THE connector for the iPhone for the next 10 years. Does everyone really think Apple is so stupid as to design something that they know would never support USB 3.0? The answer is no. They have thought about USB 3.0 support and have a plan for it. They just have just not revealed that plan yet.

How will the future Lightening adapter support an HDMI interface when HDMI uses 19 pins vs Lightening's 8 pins? I think I understand how MHL works in that it is a special 5-pin technology/data protocol that can transit the HDMI data... Is this how Apple's adapter will work? What data format/protocol will run over 8 pins to deliver audio and video?

edit: MHL WAS a proprietary TMDS-based technology from Silicon Image that is now a proposed industry standard

The Lightning to 30 pin adapter has circuitry inside the adapter to make it work. The adapter is not simply a box that routes wires from the 8 Lightening pins to pins on the 30 pin adapter. It's a smart adapter. When you plug it into the iPhone the iPhone knows thats a 30 pin adapter is connected and sends digital signals through the 8 pins into the adapter and the adapter then converts that digital data into what is needed to support the old 30 pin dock connector.

You're making it sound way more complicated and clever than it has to be. Anything you would want to do through a 30pin dock connector, with the possible exception of Firewire, can be done through standard USB device classes. HD video can be done via MHL, which is basically HDMI reconfigured to run over the USB physical link.

How will the future Lightening adapter support an HDMI interface when HDMI uses 19 pins vs Lightening's 8 pins? I think I understand how MHL works in that it is a proprietary 5-pin technology/data protocol that then converts to HDMI.. Is this how Apple's adapter will work? What data format/protocol will run over 8 pins to deliver audio and video?

From the teardown images, the connector in the phone actually only connects to one side (look at the pin the pulled out of the connector). As such, the iPhone 5 cannot ever support USB-3.

So? The iPhone 5 isn't capable of completely saturating USB 2, so there is zero reason for it to ever have a USB 3 connection. Not to mention they'd need a USB 3 compatible controller in the phone anyways... The (current) phone side doesn't matter.

Hell, the cable side doesn't even matter. When the iPhone <whatever> comes out with support for USB 3, Apple would need a new cable anyways to support USB 3 on the host end anyways. It could still be Lightning on the iPhone side, theoretically, even if current Lightning devices (iPhone 5) and current cables don't support it. Apple could, theoretically, in a future iPhone and cable have the 8 pins on each side not be shared, and use whatever technique to reconfigure the pins they already use to... reconfigure the pins to match USB 3's pin out.

I'm assuming that in addition to having just 8 data lines on the phone end, the cable also contains just 8 conductors and a shield. That would rule out all suggestions about using both sides of the connector in the future.

It's going to take an order of magnitude improvement in flash technology to render USB 2.0 too slow. By then Apple will have a new connector ready to foist upon us. How to market something as 10x faster than lightning might trouble those of us with basic science knowledge, but the general public won't care what it's called as long as it comes from their favourite fruit company.

You said it yourself. The shield in USB isn't connected to anything on the device side. So there can be a shield within the cable that connects as usual on the host side, and if the body of the Lightning plug acts as the ground, then that effectively gives them 9 pins and they're golden.

First, The shield has to carry through the connector to the device. Also, for really high-speed stuff, it may indeed be connected at both ends, though it may only be a DC ground at one end. The other end may have a cap from the shield to ground, or some other mechanism.

Second, using the shield (or the casing, if you will) of a connector for carrying a signal other then the shield for the connector is monumentally bad practice.

If I were working with an engineer who suggested that, I would probably effectively conclude he/she could not be relied upon to take proper care. I don't think I have ever seen a device that uses a connector shield for anything other then shielding.

KitsuneKnight wrote:

fake-name wrote:

From the teardown images, the connector in the phone actually only connects to one side (look at the pin the pulled out of the connector). As such, the iPhone 5 cannot ever support USB-3.

So? The iPhone 5 isn't capable of completely saturating USB 2, so there is zero reason for it to ever have a USB 3 connection. Not to mention they'd need a USB 3 compatible controller in the phone anyways... The (current) phone side doesn't matter.

Hell, the cable side doesn't even matter. When the iPhone <whatever> comes out with support for USB 3, Apple would need a new cable anyways to support USB 3 on the host end anyways. It could still be Lightning on the iPhone side, theoretically, even if current Lightning devices (iPhone 5) and current cables don't support it. Apple could, theoretically, in a future iPhone and cable have the 8 pins on each side not be shared, and use whatever technique to reconfigure the pins they already use to... reconfigure the pins to match USB 3's pin out.

Uh..... the whole point of the entire article this thread is about is referring to the lightning connector. The only device that uses the connector at the moment, and as such is what many people are discussing USB-3 with regard to is the iPhone 5.

I aggree it's ridiculous to think it needs USB-3. I'm merely pointing out that in addition to being ridiculous, it's electrically impossible, in hopes that the people hopefully talking about the lightning connector supporting USB-3 stop.

Basically, the only way the lightning connector could ever handle USB-3 is if it had more pins, e.g. the connections on each side had different functions. Since nothing on the market at the moment needs this, none of the cables will likely support it, and as such, speculation is pointless, until apple comes out with a device that sports the lightning connector and can actually utilize USB-3 speeds.

What if Lightning is the port Apple designed for the specific purpose of a Thunderbolt-native plug? That just happens to be backwards-compatible with USB, firewire, and everything else?

Thunderbolt is massive overkill and unnecessary. As it stands now, Lightning can likely already output video via MHL, and device storage is still so slow that even USB2 is underutilized when transferring data to it.

That is, if they're writing directly to the flash memory. If they're doing things the smart way they're reading data from the computer to the active RAM and letting the phone dictate when, where and how it writes that streaming data to the flash. For data transfers <= the amount of RAM the phone has USB2 or would be able to produce their full speed output, slowing only when the data fills the RAM completely and the flash hasn't been fully written to.

I don't think that it's a forgone conclusion that Apple's iPhone product roadmap includes a USB 3.0 Lightning connector at all. As xoa has pointed out above (and in comments to other articles), it will be some time before the iPhone's storage speed catches up with with the 35 - 40MB/sec speed that USB 2.0 delivers in practice. Realized speeds of a 802.11ac device at 80MHz should pick up at right about that point and only go up with wider RF bandwidth. It's not unreasonable that Apple expects to make an all-wireless or mostly-wireless transition before a physical USB 3.0 connector becomes a worthwhile proposition.

That is, if they're writing directly to the flash memory. If they're doing things the smart way they're reading data from the computer to the active RAM and letting the phone dictate when, where and how it writes that streaming data to the flash. For data transfers <= the amount of RAM the phone has USB2 or would be able to produce their full speed output, slowing only when the data fills the RAM completely and the flash hasn't been fully written to.

I'd have guessed that most/all of that RAM was already claimed by the OS and the active app(s).

On the possibility of the plug secretly having 16 pins while the port has only 8, could it not be possible that "high speed" Lightning ports could be featured on the next MacBook, having two rows of pins? Seems like you could use the same cable everywhere, and have it behave differently depending on what you plugged it in to.

Uh..... the whole point of the entire article this thread is about is referring to the lightning connector. The only device that uses the connector at the moment, and as such is what many people are discussing USB-3 with regard to is the iPhone 5.

I aggree it's ridiculous to think it needs USB-3. I'm merely pointing out that in addition to being ridiculous, it's electrically impossible, in hopes that the people hopefully talking about the lightning connector supporting USB-3 stop.

Basically, the only way the lightning connector could ever handle USB-3 is if it had more pins, e.g. the connections on each side had different functions. Since nothing on the market at the moment needs this, none of the cables will likely support it, and as such, speculation is pointless, until apple comes out with a device that sports the lightning connector and can actually utilize USB-3 speeds.

But that's my point: It doesn't matter what's in the iPhone 5, or how the current cable works specifically. It's about the port, and what it can do in the future (without breaking compatibility).

My point is what stops a future iPhone/iPad from having pins on both sides of the port (since the current one apparently has them on only one side), and a USB 3-capable Lighting cable from not having the top/bottom pins not be connected together (netting you double the number of real pins)? Nothing, really. And then you have way more than enough pins to run USB 3. It should be more than possible to make the newer USB 3 capable cable to work in the older iPhones like the iPhone 5, although just at USB 2 speeds.

Why go through all that trouble with current cables when you're no where close to needing that? If they expect Lightning to last as long as the old Dock connection, it'll quite likely go well past the shelf life of USB 2 before it's due for a replacement, so down the line Apple can start replacing the cables with USB 3 versions, when there's an iDevice that can actually use leverage USB 3's capabilities.

As for buffering in RAM? Like was said before, RAM is usually at a premium in mobile devices. iOS a while back (5.0?) switched how syncing worked, so that the device was still completely usable while the sync was active. This means it would be rather bad form to start haphazardly killing all the user's applications just to use the device' RAM so the sync will look like it ends slightly sooner (while it continues on after it claims it's done).

I'm assuming that in addition to having just 8 data lines on the phone end, the cable also contains just 8 conductors and a shield. That would rule out all suggestions about using both sides of the connector in the future.

It's going to take an order of magnitude improvement in flash technology to render USB 2.0 too slow. By then Apple will have a new connector ready to foist upon us. How to market something as 10x faster than lightning might trouble those of us with basic science knowledge, but the general public won't care what it's called as long as it comes from their favourite fruit company.

Also, even if it becomes necessary to make a new Lightning cable with more conductors, we can assume the shield is grounded at the host end. That way, the slug can be electrically connected at the tip to a spring-loaded contact there. We can have eight data lines, each with its own secondary, for LVDS signaling like we see in all the high-speed interconnects I love. Each of the two retention divots can be a high-power supply line.

And a device supporting this 19-pin "Lightning 2.0" connector will still function efficiently over USB2 with current lightning-to-USB2 cables, to the limits of the USB bus, because the negotiation of protocols is all handled by the handset.

Hold on a minute. Weren't there rumors of 18 and 19 pin connectors floating around for weeks before the "8-pin" announcement? We probably were hearing about the "Lightning 2" stuff.

The real trick will be when plugging a "Lightning-2" cable in between a USB2 host and device and making that work seamlessly, too.

That is, if they're writing directly to the flash memory. If they're doing things the smart way they're reading data from the computer to the active RAM and letting the phone dictate when, where and how it writes that streaming data to the flash. For data transfers <= the amount of RAM the phone has USB2 or would be able to produce their full speed output, slowing only when the data fills the RAM completely and the flash hasn't been fully written to.

I'd have guessed that most/all of that RAM was already claimed by the OS and the active app(s).

On the possibility of the plug secretly having 16 pins while the port has only 8, could it not be possible that "high speed" Lightning ports could be featured on the next MacBook, having two rows of pins? Seems like you could use the same cable everywhere, and have it behave differently depending on what you plugged it in to.

They did just double the RAM on the A6 chip compared to the A5, however. I'd say it's a fair bet the ram and apps could safely and happily reside in the 256 megs used on the 3GS (since, y'know, that's getting iOS6). That leaves us with 3/4 gigabyte of what's probably some flavor of DDR SDRAM to use for snarfing the first chunk of data, quite possibly enough to catch an entire sync with cache, then write it to flash at the A6's leisure.

By combining redundant grounds, I suspect the Thunderbolt electrical protocol can be routed over a "high speed" Lightning cable. And if they can do it without the need for a chip on the cable? I foresee peripheral manufacturers taking up the Lightning electrical layer awfully quickly.

Lee Hutchinson / Lee is the Senior Reviews Editor at Ars and is responsible for the product news and reviews section. He also knows stuff about enterprise storage, security, and manned space flight. Lee is based in Houston, TX.